Variable Rate Technology （VRT） takes within-field variability into consideration and aims to match resource application to crop requirement. Even though Texas is the most important cotton producing state in the US, ...Variable Rate Technology （VRT） takes within-field variability into consideration and aims to match resource application to crop requirement. Even though Texas is the most important cotton producing state in the US, the rate of VRT adoption is very low here. Hence, analyzing the factors influencing the adoption and providing a regional estimate of the impact of VRT adoption on cotton yield is very important. This study used the 2009 Southern Cotton Precision Farming Survey to analyze the farm and farmer characteristics affecting the adoption of VRT among Texas cotton farmers and to empirically estimate the impact of adoption of VRT on cotton yield in Texas. A two-stage least square procedure with a logistic regression model in the first stage and a multiple linear regression model in the second stage was used to analyze the data. The study revealed that there are significant regional differences in adoption pattern within the state of Texas; and the farmers from the coastal region, where there is higher within-field variability, were more likely to adopt VRT compared to other regions. Younger farmers, farmers managing larger farms, and farmers who use computers for farming operations were more likely to adopt VRT. The results also showed that, on an average, the adoption of VRT does not lead to significant yield improvements for cotton in Texas. Since the impact of VRT adoption on yield is not significant, the source of economic advantage of VRT adoption in Texas may be the reduction of input cost.展开更多
Center pivot irrigation systems usually apply a relatively uniform amount of water to fields that are often inherently variable, which could lead to significant waste of water and energy. To address this issue, our te...Center pivot irrigation systems usually apply a relatively uniform amount of water to fields that are often inherently variable, which could lead to significant waste of water and energy. To address this issue, our team is now developing an Intelligent Center Pivot (ICP) by integrating sensor-based irrigation scheduling with variable rate irrigation technology. However, before this technology can be applied in commercial production, it is necessary to educate growers about its practicality and potential benefits. The objective of this study was to develop a portable tabletop intelligent center pivot model (ICPDemo) to demonstrate and promote adoption of the ICP technology. This paper describes an ICPDemo constructed in 2014, including the design specifications, electro-mechanical design, control strategy, and performance. The ICPDemo has performed according to design specifications and is successfully being used to demonstrate the benefits and effectiveness of ICP technology for irrigation scheduling.展开更多
This paper describes the field tests carried out to evaluate the new Vicon RS-EDW centrifugal fertilizer spreader, to be used in Precision Agriculture. The results of initial dynamic calibration tests showed a signifi...This paper describes the field tests carried out to evaluate the new Vicon RS-EDW centrifugal fertilizer spreader, to be used in Precision Agriculture. The results of initial dynamic calibration tests showed a significant and systematic difference between the application rates of the two discs （about 20%）. This difference had to be corrected by the manufacturer that carried out the necessary changes to the electric actuators. The fertilizer spreader had good distribution homogeneity, considering different working velocities and different positions in the parcel. The pattern distribution curve for 18% super phosphate fertilizer led to an effective working width of 28 meters, with a coefficient of variation of 15%. The longitudinal test, under experimental working conditions led to a machine delay time of 6-7 seconds. The results show an actual fertilization application density between 74%-90% of that determined for each location. These results confirm that the spreader can be used to spread fertilizer differentially in the field.展开更多
A variable-bit-rate characteristic waveform interpolation （VBR-CWI） speech codec with about 1.8 kbit/s average bit rate which integrates phonetic classification into characteristic waveform （CW） decomposition is p...A variable-bit-rate characteristic waveform interpolation （VBR-CWI） speech codec with about 1.8 kbit/s average bit rate which integrates phonetic classification into characteristic waveform （CW） decomposition is proposed. Each input frame is classified into one of 4 phonetic classes. Non-speech frames are represented with Bark-band noise model. The extracted CWs become rapidly evolving waveforms （REWs） or slowly evolving waveforms （SEWs） in the cases of unvoiced or stationary voiced frames respectively, while mixed voiced frames use the same CW decomposition as that in the conventional CWI. Experimental results show that the proposed codec can eliminate most buzzy and noisy artifacts existing in the fixed-bit-rate characteristic waveform interpolation （FBR-CWI） speech codec, the average bit rate can be much lower, and its reconstructed speech quality is much better than FS 1 016 CELP at 4.8 kbit/s and similar to G. 723.1 ACELP at 5.3 kbit/s.展开更多
We consider a single server constant retrial queue,in which a state-dependent service policy is used to control the service rate.Customer arrival follows Poisson process,while service time and retrial time are exponen...We consider a single server constant retrial queue,in which a state-dependent service policy is used to control the service rate.Customer arrival follows Poisson process,while service time and retrial time are exponential distributions.Whenever the server is available,it admits the retrial customers into service based on a first-come first-served rule.The service rate adjusts in real-time based on the retrial queue length.An iterative algorithm is proposed to numerically solve the personal optimal problem in the fully observable scenario.Furthermore,we investigate the impact of parameters on the social optimal threshold.The effectiveness of the results is illustrated by two examples.展开更多
Background Chronic heart failure(CHF)is the end-stage manifestation and main cause of death of cardiovascular system diseases.Ventricular arrhythmia is a common complication,which can increase myocardial oxygen consum...Background Chronic heart failure(CHF)is the end-stage manifestation and main cause of death of cardiovascular system diseases.Ventricular arrhythmia is a common complication,which can increase myocardial oxygen consumption,aggravate the disease,and even cause sudden death due to malignant arrhythmia.As a quantitative method to evaluate cardiac autonomic nervous function,heart rate variability is non-invasive and reproducible,and can quantify the risk associated with various cardiac and non-cardiac diseases.The purpose of this study was to analyze the correlation between heart rate variability and the incidence of cardiovascular adverse events in patients with heart failure.Methods 80 patients with heart failure who were treated in our hospital from May 2020 to May 2022 were selected as the study objects.After 3 months of follow-up,patients were divided into occurrence group(n=44)and nonoccurrence group(n=36)according to the occurrence of adverse cardiovascular events(angina pectoris,myocardial infarction,arrhythmia).The index of heart rate variability and the indicators of cardiac function in patients with heart failure was analyzed by one-way analysis of variance(ANOVA).The Key indicators of heart rate variability include standard deviation of normal RR interval(SDNN),mean standard deviation of consecutive 5-minute heartbeat interval(SDANN),square root of mean square of difference between adjacent heartbeat intervals(RMSSD),and percentage of RR intervals differing more than 50 ms from the preceding one(PNN50).The indicators of cardiac function include the New York Heart Association(NYHA)functional classification,left ventricular ejection fraction(LVEF),brain natriuretic peptide(BNP)and cardiac troponin I(c Tn I).Multivariate logistic regression was used to analyze the incidence of cardiovascular adverse events in patients with heart failure.Receiver operating characteristic(ROC)curve was used to analyze the predictive value of heart rate variability in patient outcomes.The correlation between heart rate variability and the incidence of cardiovascular adverse events was analyzed by Kendall's tau-b analysis.Results There were significant differences in SDNN,SDANN,RMSSD,PNN50,cardiac function grade,LVEF and BNP level between the two groups(P<0.05).Through logistic regression analysis,SDNN,SDANN,RMSSD and PNN50 were independent predictors for the incidence of cardiovascular adverse events(P<0.05).The areas under curve for SDNN,SDANN,RMSSD,and PNN50 predicting of the incidence of cardiovascular adverse events were 0.732,0.732,0.758,and 0.819 respectively,and the sensitivity was 77.27%,81.81%,75.00%and 65.91%,respectively.The specificity was 61.11%,61.11%,80.56%,83.33%(P<0.05),respectively.Through Kendall's tau-b analysis,the index of heart rate variability was negatively correlated with the incidence of adverse cardiovascular events in patients with prognosis(P<0.05).Conclusions Heart rate variability has predictive value for the incidence of adverse cardiovascular events in patients with heart failure.The lower the heart rate variability,the higher incidence of cardiovascular adverse events.[S Chin J Cardiol 2024;25(3):135-141]展开更多
In this article,Deng and Song showed compelling evidence on the connection between heart rate variability(HRV)alterations and cancer in 127 cancer patients compared with healthy reference individuals,highlighting auto...In this article,Deng and Song showed compelling evidence on the connection between heart rate variability(HRV)alterations and cancer in 127 cancer patients compared with healthy reference individuals,highlighting autonomic nervous system dysfunction as a significant physiological manifestation in cancer patients.We discussed that the reduced HRV may be associated with cancer treatments,e.g.,operation,chemotherapy and pain control and psychological response such as depression and anxiety related to the affected cancer.A management such as medicine to mood disturbances related to cancer has been shown a benefit to improve HRV in cancer patients.展开更多
BACKGROUND Heart rate variability(HRV)represents efferent vagus nerve activity,which is suggested to be related to fundamental mechanisms of tumorigenesis and to be a predictor of prognosis in various cancers.Therefor...BACKGROUND Heart rate variability(HRV)represents efferent vagus nerve activity,which is suggested to be related to fundamental mechanisms of tumorigenesis and to be a predictor of prognosis in various cancers.Therefore,this study hypothesized that HRV monitoring could predict perioperative complication(PC)in colorectal cancer(CRC)patients.AIM To investigate the prognostic value of HRV in hospitalized CRC patients.METHODS The observational studies included 87 patients who underwent CRC surgical procedures under enhanced recovery after surgery programs in a first-class hospital.The HRV parameters were compared between the PC group and the non PC(NPC)group from preoperative day 1 to postoperative day(Pod)3.In addition,inflammatory biomarkers and nutritional indicators were also analyzed.RESULTS The complication rate was 14.9%.HRV was markedly abnormal after surgery,especially in the PC group.The frequency-domain parameters(including pNN50)and time-domain parameters[including high-frequency(HF)]of HRV were significantly different between the two groups postoperatively.The pNN50 was significantly greater at Pod1 in the PC group than that in the NPC group and returned to baseline at Pod2,suggesting that patients with complications exhibited autonomic nerve dysfunction in the early postoperative period.In the PC group,HFs were also enhanced from Pod1 and were significantly higher than in the NPC group;inflammatory biomarkers were significantly elevated at Pod2 and Pod3;the levels of nutritional indicators were significantly lower at Pod1 and Pod2;and the white blood cell count was slightly elevated at Pod3.CONCLUSION HRV is independently associated with postoperative complications in patients with CRC.Abnormal HRV could predicted an increased risk of postoperative complications in CRC patients.Continuous HRV could be used to monitor complications in patients with CRC during the perioperative period.展开更多
Purpose:To explore the clinical value of Electromyography(EMG)and Heart Rate Variability(HRV)in the diagnosis of early DPN and provide the basis for early diagnosis,treatment,and prevention of DPN.Methods:105 patients...Purpose:To explore the clinical value of Electromyography(EMG)and Heart Rate Variability(HRV)in the diagnosis of early DPN and provide the basis for early diagnosis,treatment,and prevention of DPN.Methods:105 patients with type 2 diabetes mellitus(T2DM)in the Changji People’s Hospital were treated from January 2023 to December 2023.They were stratifi ed into DPN-symptomatic(DPN group,n=55)and DPN-asymptomatic(NDPN group,n=50)cohorts based on the presence or absence of clinically confi rmed diabetic peripheral neuropathy.The clinical biochemical indicators,nerve electromyography,and HRV parameters were obtained from electronic medical records,and diff erences in detection results were compared between the two groups.Logistic regression was applied to analyze the infl uencing factors of DPN in diabetes patients.The receiver operating characteristic(ROC)curve was applied to analyze the diagnostic value of EMG combined with other parameters for DPN.Results:From the results of the general information,diabetes duration,glycosylated hemoglobin(HbA1c),low-density lipoprotein cholesterol(LDL-C),total cholesterol(TC)and FBG in the DPN group were significantly differences compared with the NDPN group(p<0.05).There were no statistically significant differences in gender,age years,uric acid,and other general data(p>0.05).Compared with the NDPN group,the motor nerve conduction velocity(MNCV),sensory nerve conduction velocity(SNCV)of the ulnar nerve,median nerve,and tibial nerve in the DPN group were statistically signifi cant(p>0.05).The DPN group had higher average F wave latency and H wave latency in the tested nerve,with statistical signifi cance(p<0.05).HRV parameters decreased signifi cantly(SDNN,rMSSD,PNN50,and SDANN,all p<0.05).ROC analysis showed that the area under the ROC curve(AUC)of the combined diagnosis of DPN by duration of diabetes,HbA1c,EMG,and HRV was 0.897,the accuracy was 82.86%,the sensitivity was 78.00%,and the specifi city was 87.27%.The AUC of the combined diagnosis of the four parameters for DPN was signifi cantly higher than that of each alone(p<0.05).Conclusion:The combination of EMG and HRV has a high value in the assessment of DPN and can be used for early assessment of the extent of the lesion.展开更多
BACKGROUND Depression is a common comorbidity in patients with chronic obstructive pulmonary disease(COPD).Research indicates that COPD affects cardiac au-tonomic control,and heart rate variability(HRV)serves as a sim...BACKGROUND Depression is a common comorbidity in patients with chronic obstructive pulmonary disease(COPD).Research indicates that COPD affects cardiac au-tonomic control,and heart rate variability(HRV)serves as a simple,non-invasive measure of autonomic nerve activity.However,the relationship between HRV and lung function,as well as the impact of depressive symptoms,remains un-clear.METHODS A retrospective cross-sectional study involving 120 COPD patients hospitalized from January 2018 to January 2024 at our institution was conducted.Demographic and clinical characteristics were collected,and depressive symptoms were asse-ssed using the Beck Depression Inventory(BDI).Patients were categorized into a depressed group(BDI≥16)and a non-depressed group(BDI<16).A control group consisting of 60 healthy volunteers who underwent check-ups at the same institution was also included.Statistical analyses were performed using SPSS 26.0 software.Pearson correlation coefficients were calculated to determine and compare the relationships between HRV parameters,lung function measures,and RESULTS Of the 120 patients with COPD,35.8%(43/120)were diagnosed with depression,compared to 5.0%(3/60)in the control group.The HRV index in COPD patients was significantly lower than that in the control group(P<0.05),and the value in the depressed group was significantly lower than that in the non-depressed group(P<0.05).Similarly,the COPD group had a significantly lower pulmonary forced vital capacity(FVC),first-second expiratory volume(FEV1)and FEV1/FVC ratios than the control group(P<0.05),and the depressed group was significantly lower than that in the non-depressed group(P<0.05).Pearson correlation analysis revealed that the standard deviation of normal R-R intervals,standard deviation of the mean of 5-minute normal R-R intervals,root mean square of successive differences of normal R-R intervals,percentage of normal R-R intervals greater than 50 ms,high-frequency,and low-frequency indices showed positive correlations with lung function parameters(P<0.05)and negative correlations with BDI scores(P<0.05).CONCLUSION Compared to patients without COPD,the incidence of depressive symptoms is higher among patients with COPD and is negatively correlated with the patients’HRV indices.In contrast,HRV indices are positively correlated with the patients’pulmonary function parameters.Patients and healthcare professionals should enhance their awareness of depression,actively conduct depression assessment screenings,and incorporate HRV indices into disease management.This approach aims to improve the psychological health of patients and ultimately enhance their prognosis and quality of life.展开更多
In this article,we comment on the study by Yang et al,which demonstrated significant cross-sectional associations between heart rate variability(HRV)indices,depressive symptoms,and lung function in patients with chron...In this article,we comment on the study by Yang et al,which demonstrated significant cross-sectional associations between heart rate variability(HRV)indices,depressive symptoms,and lung function in patients with chronic obstructive pulmonary disease(COPD).Building on these findings,we further explore the underlying mechanisms,particularly inflammatory-autonomic-oxidative stress pathways,as key causal mediators.Moreover,analyzing genetic polymorphisms alongside environmental factors may uncover susceptibility pathways explaining interindividual differences in HRV and comorbidity risk.Additionally,longitudinal studies tracking HRV trajectories could identify thresholds predictive of accelerated lung function decline or cardiovascular events,informing personalized prevention strategies.Integrating longitudinal HRV data with multi-omics biomarkers and machine learning models could enable real-time prediction of depression relapses or COPD exacerbations,facilitating proactive interventions such as personalized biofeedback training or precision anti-inflammatory therapies.By synthesizing these perspectives,this integrative approach promises to advance precision medicine for COPD patients,particularly those with comorbid depression,by addressing both mechanistic insights and clinical translation.展开更多
BACKGROUND A significant proportion of cancer patients experience autonomic dysfunction,and cancer treatments such as chemotherapy and radiation therapy can exacerbate impairments in the cardiac autonomic nervous syst...BACKGROUND A significant proportion of cancer patients experience autonomic dysfunction,and cancer treatments such as chemotherapy and radiation therapy can exacerbate impairments in the cardiac autonomic nervous system.This study sought to investigate the characteristics of heart rate variability(HRV)in individuals with cancer.AIM To evaluate the relationship between HRV and cancer patients,providing insights and references for cancer treatment.METHODS The study included 127 cancer patients with available 24-hour dynamic electrocardiogram data.HRV differences were analyzed using both time domain and frequency domain methods.These findings were then compared to HRV data from reference individuals,sourced from literature that utilized the same HRV computing algorithm.RESULTS Our findings revealed that cancer patients generally exhibited abnormal HRV compared to the reference group.HRV was found to be correlated with age and clinical type(P<0.05),but no significant correlation was observed with tumor site or gender(P>0.05).CONCLUSION This study indicates that cancer patients have significantly abnormal HRV compared to reference individuals,suggesting the presence of a certain level of cardiac autonomic dysfunction in this patient population.展开更多
Autonomic dysfunction(AD)is frequently observed in cirrhotic patients and is associated with poor clinical outcomes and prognoses.Heart rate variability(HRV),a noninvasive tool for assessing autonomic nervous system b...Autonomic dysfunction(AD)is frequently observed in cirrhotic patients and is associated with poor clinical outcomes and prognoses.Heart rate variability(HRV),a noninvasive tool for assessing autonomic nervous system balance,has been extensively studied in a variety of conditions,including chronic liver disease(CLD);however,no recent reviews have focused on its role in CLD.This article examines the mechanisms of AD in CLD and the foundation for HRV assessment,highlighting its diagnostic,prognostic,and therapeutic applications in CLD,including liver transplantation(LT).Changes in HRV,particularly in patients with cirrhotic complications,and its prognostic significance throughout the natural history of CLD are summarized.We show that HRV is consistently reduced in CLD patients,reflecting AD,and is inversely correlated with liver disease severity.Also,low HRV is associated with complications such as hepatic encephalopathy,ascites,and portal hypertension.Moreover,evidence indicates that reduced HRV is an independent risk factor for mortality and circulatory instability in CLD.Furthermore,treatment with beta-blockers and LT improves HRV,underscoring its potential role in patient management.While further studies are needed,HRV emerges as a promising tool for the comprehensive evaluation and clinical management of patients with CLD,offering insights into disease progression and therapeutic response.展开更多
This paper presented a novel variable rate fertilization system based on the method of adjusting the active feed-roll length of a fluted roller.The feasibility of this method was discussed using analysis of the fluted...This paper presented a novel variable rate fertilization system based on the method of adjusting the active feed-roll length of a fluted roller.The feasibility of this method was discussed using analysis of the fluted roller model.One seed drill produced by Kuhn Company(France),which could sow and fertilize simultaneously,was used as a test platform to implement the mechanical structure of variable rate fertilization.The design methods for the variable rate fertilization mechanical structure and actuator were introduced in detail.A low-cost and stable embedded support decision subsystem and corresponding software were developed.The support decision subsystem is based on grid management.Each grid field cell contains information about corresponding spatial position and fertilizer application rate.A SpatiaLite database was employed to solve the spatial location search and spatial data query.Experiments were conducted to evaluate the fertilization uniformity and dynamic response time.The average value of coefficient of variation is 8.4%in five different active feed-roll lengths which reflects good uniformity.The dynamic response times for the adjustment of variable rate fertilization system from 204 kg/hm^(2) to 319 kg/hm^(2) and 319 kg/hm^(2) to 204 kg/hm^(2) are about 4.2 s.The results suggest that the variable rate fertilization system performs well in dynamic adjustment and stability.展开更多
During different growth periods,canopy size and density in orchards are variable,which need application conditions(flow rate and air flow)to be adjusted to match the canopy’s characteristics.In order to improve orcha...During different growth periods,canopy size and density in orchards are variable,which need application conditions(flow rate and air flow)to be adjusted to match the canopy’s characteristics.In order to improve orchard sprayer’s automatic operating performance,an automatic variable-rate orchard sprayer(VARS)fixed with 40 electromagnetic valves and 8 brushless fans was developed based on the canopy’s spatial dimensions.Each solenoid valve and brushless motor can be individually adjusted in real-time through pulse width modulation(PWM)signals emitted by a control system to adjust each nozzle’s spout and fan rotation speed.A high-precision laser scanning sensor(light detecting and ranging,LIDAR)was adopted as the detector to measure the canopy volume using the variable rate algorithm principle.Field experiments were conducted in an apple orchard,and conventional air blast sprayer(CABS)and directed air-jet sprayer(DAJS)were tested as a comparison.Results showed that on average,46%less spraying solution was applied compared to conventional applications,while penetration rate was similar to DAJS.Normalized deposition in the canopy with variable application was higher than that of conventional applications,indicating that electronic sprayers are more efficient than conventional sprayers.It was also observed that VARS could significantly reduce off-target loss.The field experiment showed that the newly developed variable-rate sprayer can greatly reduce pesticide use and protect the environment for the orchard fruit production,and also provide a reference for design and performance optimization for plant protection machinery.展开更多
The rapid developments of unmanned aerial vehicles(UAV)and vision sensor are contributing a great reformation in precision agriculture.Farmers can fly their UAV spraying pesticides around their crop fields while stayi...The rapid developments of unmanned aerial vehicles(UAV)and vision sensor are contributing a great reformation in precision agriculture.Farmers can fly their UAV spraying pesticides around their crop fields while staying at their remote control room or any place that is separated from their farm land.However,there is a common phenomenon in rice planting management stage that some empty areas are randomly located in farmland.Therefore,a critical problem is that the waste of pesticides that occurs when spraying pesticides over rice fields with empty areas by using the common UAV,because it is difficult to control the flow accuracy based on the empty areas changing.To tackle this problem,a novel vision-based spraying system was proposed that can identify empty areas automatically while spraying a precise amount of pesticides on the target regions.By this approach,the image was preprocessed with the Lucy-Richardson algorithm,then the target area was split from the background with k-means and the feature parameters were extracted,finally the feature parameters were filtered out with a positive contribution which would serve as the input parameters of the support vector machine(SVM)to identify the target area.Also a fuzzy control model was analyzed and exerted to compensate the nonlinearity and hysteresis of the variable rate spraying system.Experimental results proved that the approach was applicable to reducing the amount of pesticides during UAV spraying,which can provide a reference for precision agriculture aviation in the future.展开更多
Environmental impact and economic concerns have driven a variable rate technology(VRT).Spinner spreaders were mainly used for granular fertilizer application since they are simple in design,inexpensive,and can cover l...Environmental impact and economic concerns have driven a variable rate technology(VRT).Spinner spreaders were mainly used for granular fertilizer application since they are simple in design,inexpensive,and can cover large areas.However,the spreader was not adequate for VRT because uniformity changes drastically while varying application rates.Thus,the purpose of this study was to develop a variable rate applicator with uniform spreading patterns.A commercial spreader was modified with a controller and electric actuators for controlling fertilizer discharge directions and amounts.Database was established to determine the optimum discharge direction according to the fertilizer application amount.The uniformity of spreading patterns in accordance with the spread amount per set unit area was evaluated by the statistical coefficient of variation(CV)lower than 15%is assumed to prevent damage to the crop.Test results showed that CVs were 8%,9%,and 8%,respectively,for a tractor in race track mode(adjacent passes in same direction of travel)at 200 kg/hm^(2),300 kg/hm^(2),and 400 kg/hm^(2).This indicates that the fertilizer was spread uniformly,while the coefficient of variation was 12%at 200 kg/hm^(2) in back and forth mode(adjacent passes in the opposite direction of travel).Overall,the results suggest that the race track mode is suitable for operation of a tractor to ensure uniform spreading of fertilizer when applying at variable rates.The future goal is to establish a system for automatic variable rate application according to location in connection with soil analysis and geographic information systems.展开更多
The key technical problem of variable rate fertilization system based on spectrum information was precise variable fertilization in certain area according to the acquired spectrum information.Hysteretic fertilizing is...The key technical problem of variable rate fertilization system based on spectrum information was precise variable fertilization in certain area according to the acquired spectrum information.Hysteretic fertilizing is a critical problem in most of current fertilizer equipment.Hysteresis model was built and analyzed in this study to improve the system.Fertilizing tests were conducted on different wheat breeds and the results were analyzed.The tests showed that variable rate fertilization had obvious hysteresis phenomenon with the maximum lag distance of 3.82 m,the minimum lag distance of 1.73 m and average of 3.06 m.Hysteresis phenomenon of the variable rate fertilization system was obviously decreased when implanting a correction time of 2.04 s with the maximum lag distance of 0.61 m.Variable effects varied by different wheat breeds.Variable rate fertilization had an advantage of improving spatial differences of Yangmai-23,and the spatial variability of which decreased by 14.23%.In the small test area,the amount of fertilizer in Zhenmai-168 decreased by 2.84 kg,while the amount of which in Yangmai-23 increased by 3.83 kg.Yield of Zhenmai-168 in small area was lower than that in traditional pattern,but the condition of Yangmai-23 was on the contrary.Valuable information for increasing performance of fertilization in variable rate fertilization system was provided in this paper.展开更多
In order to improve soil fertility and fertilizer utilization,a subsoiling variable rate fertilization machine based on conservation tillage and precision agriculture was designed and tested.The relationship between s...In order to improve soil fertility and fertilizer utilization,a subsoiling variable rate fertilization machine based on conservation tillage and precision agriculture was designed and tested.The relationship between suspension parameters and penetrating distance was analyzed,and a matching model between fertilizing quantity and penetrating distance was established.The variable rate fertilization control machine was developed based on an Advantech PCM-9363 industrial control mainboard.The machine operates under two patterns:DGPS-based positioning and straight-line path positioning based on a planar coordinate system.This machine can perform on-demand fertilization according to the spatial differences in soil nutrients and the prescription maps pre-set before the operation.Field experiments showed the machine has a subsoiling stability of 92.5%,a soil breaking rate of 61.1%,a maximum positioning relative error of 2.68%and a maximum variable rate fertilization error of 3.89%.The subsoiling performance and variable rate fertilization indices of this machine satisfy the requirements of GB/T24675.2-2009.The tested indices meet the national and industrial standards and satisfy the design requirements.The findings of the research can be used as the structural design of the subsoiling variable rate fertilization machine.展开更多
To address the problem of maneuvering target tracking, where the target trajectory has prolonged smooth regions and abrupt maneuvering regions, a modified variable rate particle filter （MVRPF） is proposed. First, a ...To address the problem of maneuvering target tracking, where the target trajectory has prolonged smooth regions and abrupt maneuvering regions, a modified variable rate particle filter （MVRPF） is proposed. First, a Cartesian-coordinate based variable rate model is presented. Compared with conventional variable rate models, the proposed model does not need any prior knowledge of target mass or external forces. Consequently, it is more convenient in practical tracking applications. Second, a maneuvering detection strategy is adopted to adaptively adjust the parameters in MVRPF, which helps allocate more state points at high maneuver regions and fewer at smooth regions. Third, in the presence of small measurement errors, the unscented particle filter, which is embedded in MVRPF, can move more particles into regions of high likelihood and hence can improve the tracking performance. Simulation results illustrate the effectiveness of the proposed method.展开更多
文摘Variable Rate Technology （VRT） takes within-field variability into consideration and aims to match resource application to crop requirement. Even though Texas is the most important cotton producing state in the US, the rate of VRT adoption is very low here. Hence, analyzing the factors influencing the adoption and providing a regional estimate of the impact of VRT adoption on cotton yield is very important. This study used the 2009 Southern Cotton Precision Farming Survey to analyze the farm and farmer characteristics affecting the adoption of VRT among Texas cotton farmers and to empirically estimate the impact of adoption of VRT on cotton yield in Texas. A two-stage least square procedure with a logistic regression model in the first stage and a multiple linear regression model in the second stage was used to analyze the data. The study revealed that there are significant regional differences in adoption pattern within the state of Texas; and the farmers from the coastal region, where there is higher within-field variability, were more likely to adopt VRT compared to other regions. Younger farmers, farmers managing larger farms, and farmers who use computers for farming operations were more likely to adopt VRT. The results also showed that, on an average, the adoption of VRT does not lead to significant yield improvements for cotton in Texas. Since the impact of VRT adoption on yield is not significant, the source of economic advantage of VRT adoption in Texas may be the reduction of input cost.
文摘Center pivot irrigation systems usually apply a relatively uniform amount of water to fields that are often inherently variable, which could lead to significant waste of water and energy. To address this issue, our team is now developing an Intelligent Center Pivot (ICP) by integrating sensor-based irrigation scheduling with variable rate irrigation technology. However, before this technology can be applied in commercial production, it is necessary to educate growers about its practicality and potential benefits. The objective of this study was to develop a portable tabletop intelligent center pivot model (ICPDemo) to demonstrate and promote adoption of the ICP technology. This paper describes an ICPDemo constructed in 2014, including the design specifications, electro-mechanical design, control strategy, and performance. The ICPDemo has performed according to design specifications and is successfully being used to demonstrate the benefits and effectiveness of ICP technology for irrigation scheduling.
文摘This paper describes the field tests carried out to evaluate the new Vicon RS-EDW centrifugal fertilizer spreader, to be used in Precision Agriculture. The results of initial dynamic calibration tests showed a significant and systematic difference between the application rates of the two discs （about 20%）. This difference had to be corrected by the manufacturer that carried out the necessary changes to the electric actuators. The fertilizer spreader had good distribution homogeneity, considering different working velocities and different positions in the parcel. The pattern distribution curve for 18% super phosphate fertilizer led to an effective working width of 28 meters, with a coefficient of variation of 15%. The longitudinal test, under experimental working conditions led to a machine delay time of 6-7 seconds. The results show an actual fertilization application density between 74%-90% of that determined for each location. These results confirm that the spreader can be used to spread fertilizer differentially in the field.
文摘A variable-bit-rate characteristic waveform interpolation （VBR-CWI） speech codec with about 1.8 kbit/s average bit rate which integrates phonetic classification into characteristic waveform （CW） decomposition is proposed. Each input frame is classified into one of 4 phonetic classes. Non-speech frames are represented with Bark-band noise model. The extracted CWs become rapidly evolving waveforms （REWs） or slowly evolving waveforms （SEWs） in the cases of unvoiced or stationary voiced frames respectively, while mixed voiced frames use the same CW decomposition as that in the conventional CWI. Experimental results show that the proposed codec can eliminate most buzzy and noisy artifacts existing in the fixed-bit-rate characteristic waveform interpolation （FBR-CWI） speech codec, the average bit rate can be much lower, and its reconstructed speech quality is much better than FS 1 016 CELP at 4.8 kbit/s and similar to G. 723.1 ACELP at 5.3 kbit/s.
基金supported by the National Natural Science Foundation of China(Grant No.11971486)。
文摘We consider a single server constant retrial queue,in which a state-dependent service policy is used to control the service rate.Customer arrival follows Poisson process,while service time and retrial time are exponential distributions.Whenever the server is available,it admits the retrial customers into service based on a first-come first-served rule.The service rate adjusts in real-time based on the retrial queue length.An iterative algorithm is proposed to numerically solve the personal optimal problem in the fully observable scenario.Furthermore,we investigate the impact of parameters on the social optimal threshold.The effectiveness of the results is illustrated by two examples.
文摘Background Chronic heart failure(CHF)is the end-stage manifestation and main cause of death of cardiovascular system diseases.Ventricular arrhythmia is a common complication,which can increase myocardial oxygen consumption,aggravate the disease,and even cause sudden death due to malignant arrhythmia.As a quantitative method to evaluate cardiac autonomic nervous function,heart rate variability is non-invasive and reproducible,and can quantify the risk associated with various cardiac and non-cardiac diseases.The purpose of this study was to analyze the correlation between heart rate variability and the incidence of cardiovascular adverse events in patients with heart failure.Methods 80 patients with heart failure who were treated in our hospital from May 2020 to May 2022 were selected as the study objects.After 3 months of follow-up,patients were divided into occurrence group(n=44)and nonoccurrence group(n=36)according to the occurrence of adverse cardiovascular events(angina pectoris,myocardial infarction,arrhythmia).The index of heart rate variability and the indicators of cardiac function in patients with heart failure was analyzed by one-way analysis of variance(ANOVA).The Key indicators of heart rate variability include standard deviation of normal RR interval(SDNN),mean standard deviation of consecutive 5-minute heartbeat interval(SDANN),square root of mean square of difference between adjacent heartbeat intervals(RMSSD),and percentage of RR intervals differing more than 50 ms from the preceding one(PNN50).The indicators of cardiac function include the New York Heart Association(NYHA)functional classification,left ventricular ejection fraction(LVEF),brain natriuretic peptide(BNP)and cardiac troponin I(c Tn I).Multivariate logistic regression was used to analyze the incidence of cardiovascular adverse events in patients with heart failure.Receiver operating characteristic(ROC)curve was used to analyze the predictive value of heart rate variability in patient outcomes.The correlation between heart rate variability and the incidence of cardiovascular adverse events was analyzed by Kendall's tau-b analysis.Results There were significant differences in SDNN,SDANN,RMSSD,PNN50,cardiac function grade,LVEF and BNP level between the two groups(P<0.05).Through logistic regression analysis,SDNN,SDANN,RMSSD and PNN50 were independent predictors for the incidence of cardiovascular adverse events(P<0.05).The areas under curve for SDNN,SDANN,RMSSD,and PNN50 predicting of the incidence of cardiovascular adverse events were 0.732,0.732,0.758,and 0.819 respectively,and the sensitivity was 77.27%,81.81%,75.00%and 65.91%,respectively.The specificity was 61.11%,61.11%,80.56%,83.33%(P<0.05),respectively.Through Kendall's tau-b analysis,the index of heart rate variability was negatively correlated with the incidence of adverse cardiovascular events in patients with prognosis(P<0.05).Conclusions Heart rate variability has predictive value for the incidence of adverse cardiovascular events in patients with heart failure.The lower the heart rate variability,the higher incidence of cardiovascular adverse events.[S Chin J Cardiol 2024;25(3):135-141]
文摘In this article,Deng and Song showed compelling evidence on the connection between heart rate variability(HRV)alterations and cancer in 127 cancer patients compared with healthy reference individuals,highlighting autonomic nervous system dysfunction as a significant physiological manifestation in cancer patients.We discussed that the reduced HRV may be associated with cancer treatments,e.g.,operation,chemotherapy and pain control and psychological response such as depression and anxiety related to the affected cancer.A management such as medicine to mood disturbances related to cancer has been shown a benefit to improve HRV in cancer patients.
基金Supported by The Natural Science Foundation of Nanjing University of Chinese Medicine,No.XZR2021019The Outstanding Young Doctor Program of Jiangsu Province of Chinese Medicine,No.2023QB0140+1 种基金Project of National Clinical Research Base of Traditional Chinese Medicine in Jiangsu Province,No.JD2022SZ18The Natural Science Foundation of Nanjing University of Chinese Medicine,No.KYCX21_1710.
文摘BACKGROUND Heart rate variability(HRV)represents efferent vagus nerve activity,which is suggested to be related to fundamental mechanisms of tumorigenesis and to be a predictor of prognosis in various cancers.Therefore,this study hypothesized that HRV monitoring could predict perioperative complication(PC)in colorectal cancer(CRC)patients.AIM To investigate the prognostic value of HRV in hospitalized CRC patients.METHODS The observational studies included 87 patients who underwent CRC surgical procedures under enhanced recovery after surgery programs in a first-class hospital.The HRV parameters were compared between the PC group and the non PC(NPC)group from preoperative day 1 to postoperative day(Pod)3.In addition,inflammatory biomarkers and nutritional indicators were also analyzed.RESULTS The complication rate was 14.9%.HRV was markedly abnormal after surgery,especially in the PC group.The frequency-domain parameters(including pNN50)and time-domain parameters[including high-frequency(HF)]of HRV were significantly different between the two groups postoperatively.The pNN50 was significantly greater at Pod1 in the PC group than that in the NPC group and returned to baseline at Pod2,suggesting that patients with complications exhibited autonomic nerve dysfunction in the early postoperative period.In the PC group,HFs were also enhanced from Pod1 and were significantly higher than in the NPC group;inflammatory biomarkers were significantly elevated at Pod2 and Pod3;the levels of nutritional indicators were significantly lower at Pod1 and Pod2;and the white blood cell count was slightly elevated at Pod3.CONCLUSION HRV is independently associated with postoperative complications in patients with CRC.Abnormal HRV could predicted an increased risk of postoperative complications in CRC patients.Continuous HRV could be used to monitor complications in patients with CRC during the perioperative period.
基金supported by the Key Program of the Changji Prefecture Science and Technology Program(2023S04-10,2023S06-03).
文摘Purpose:To explore the clinical value of Electromyography(EMG)and Heart Rate Variability(HRV)in the diagnosis of early DPN and provide the basis for early diagnosis,treatment,and prevention of DPN.Methods:105 patients with type 2 diabetes mellitus(T2DM)in the Changji People’s Hospital were treated from January 2023 to December 2023.They were stratifi ed into DPN-symptomatic(DPN group,n=55)and DPN-asymptomatic(NDPN group,n=50)cohorts based on the presence or absence of clinically confi rmed diabetic peripheral neuropathy.The clinical biochemical indicators,nerve electromyography,and HRV parameters were obtained from electronic medical records,and diff erences in detection results were compared between the two groups.Logistic regression was applied to analyze the infl uencing factors of DPN in diabetes patients.The receiver operating characteristic(ROC)curve was applied to analyze the diagnostic value of EMG combined with other parameters for DPN.Results:From the results of the general information,diabetes duration,glycosylated hemoglobin(HbA1c),low-density lipoprotein cholesterol(LDL-C),total cholesterol(TC)and FBG in the DPN group were significantly differences compared with the NDPN group(p<0.05).There were no statistically significant differences in gender,age years,uric acid,and other general data(p>0.05).Compared with the NDPN group,the motor nerve conduction velocity(MNCV),sensory nerve conduction velocity(SNCV)of the ulnar nerve,median nerve,and tibial nerve in the DPN group were statistically signifi cant(p>0.05).The DPN group had higher average F wave latency and H wave latency in the tested nerve,with statistical signifi cance(p<0.05).HRV parameters decreased signifi cantly(SDNN,rMSSD,PNN50,and SDANN,all p<0.05).ROC analysis showed that the area under the ROC curve(AUC)of the combined diagnosis of DPN by duration of diabetes,HbA1c,EMG,and HRV was 0.897,the accuracy was 82.86%,the sensitivity was 78.00%,and the specifi city was 87.27%.The AUC of the combined diagnosis of the four parameters for DPN was signifi cantly higher than that of each alone(p<0.05).Conclusion:The combination of EMG and HRV has a high value in the assessment of DPN and can be used for early assessment of the extent of the lesion.
基金Supported by the Zhangjiakou City Science and Technology Research Plan,No.1821110D.
文摘BACKGROUND Depression is a common comorbidity in patients with chronic obstructive pulmonary disease(COPD).Research indicates that COPD affects cardiac au-tonomic control,and heart rate variability(HRV)serves as a simple,non-invasive measure of autonomic nerve activity.However,the relationship between HRV and lung function,as well as the impact of depressive symptoms,remains un-clear.METHODS A retrospective cross-sectional study involving 120 COPD patients hospitalized from January 2018 to January 2024 at our institution was conducted.Demographic and clinical characteristics were collected,and depressive symptoms were asse-ssed using the Beck Depression Inventory(BDI).Patients were categorized into a depressed group(BDI≥16)and a non-depressed group(BDI<16).A control group consisting of 60 healthy volunteers who underwent check-ups at the same institution was also included.Statistical analyses were performed using SPSS 26.0 software.Pearson correlation coefficients were calculated to determine and compare the relationships between HRV parameters,lung function measures,and RESULTS Of the 120 patients with COPD,35.8%(43/120)were diagnosed with depression,compared to 5.0%(3/60)in the control group.The HRV index in COPD patients was significantly lower than that in the control group(P<0.05),and the value in the depressed group was significantly lower than that in the non-depressed group(P<0.05).Similarly,the COPD group had a significantly lower pulmonary forced vital capacity(FVC),first-second expiratory volume(FEV1)and FEV1/FVC ratios than the control group(P<0.05),and the depressed group was significantly lower than that in the non-depressed group(P<0.05).Pearson correlation analysis revealed that the standard deviation of normal R-R intervals,standard deviation of the mean of 5-minute normal R-R intervals,root mean square of successive differences of normal R-R intervals,percentage of normal R-R intervals greater than 50 ms,high-frequency,and low-frequency indices showed positive correlations with lung function parameters(P<0.05)and negative correlations with BDI scores(P<0.05).CONCLUSION Compared to patients without COPD,the incidence of depressive symptoms is higher among patients with COPD and is negatively correlated with the patients’HRV indices.In contrast,HRV indices are positively correlated with the patients’pulmonary function parameters.Patients and healthcare professionals should enhance their awareness of depression,actively conduct depression assessment screenings,and incorporate HRV indices into disease management.This approach aims to improve the psychological health of patients and ultimately enhance their prognosis and quality of life.
文摘In this article,we comment on the study by Yang et al,which demonstrated significant cross-sectional associations between heart rate variability(HRV)indices,depressive symptoms,and lung function in patients with chronic obstructive pulmonary disease(COPD).Building on these findings,we further explore the underlying mechanisms,particularly inflammatory-autonomic-oxidative stress pathways,as key causal mediators.Moreover,analyzing genetic polymorphisms alongside environmental factors may uncover susceptibility pathways explaining interindividual differences in HRV and comorbidity risk.Additionally,longitudinal studies tracking HRV trajectories could identify thresholds predictive of accelerated lung function decline or cardiovascular events,informing personalized prevention strategies.Integrating longitudinal HRV data with multi-omics biomarkers and machine learning models could enable real-time prediction of depression relapses or COPD exacerbations,facilitating proactive interventions such as personalized biofeedback training or precision anti-inflammatory therapies.By synthesizing these perspectives,this integrative approach promises to advance precision medicine for COPD patients,particularly those with comorbid depression,by addressing both mechanistic insights and clinical translation.
基金the Medical Ethics Committee of the Hefei Cancer Hospital,Chinese Academy of Sciences(No.PJ-KY-2024-025).
文摘BACKGROUND A significant proportion of cancer patients experience autonomic dysfunction,and cancer treatments such as chemotherapy and radiation therapy can exacerbate impairments in the cardiac autonomic nervous system.This study sought to investigate the characteristics of heart rate variability(HRV)in individuals with cancer.AIM To evaluate the relationship between HRV and cancer patients,providing insights and references for cancer treatment.METHODS The study included 127 cancer patients with available 24-hour dynamic electrocardiogram data.HRV differences were analyzed using both time domain and frequency domain methods.These findings were then compared to HRV data from reference individuals,sourced from literature that utilized the same HRV computing algorithm.RESULTS Our findings revealed that cancer patients generally exhibited abnormal HRV compared to the reference group.HRV was found to be correlated with age and clinical type(P<0.05),but no significant correlation was observed with tumor site or gender(P>0.05).CONCLUSION This study indicates that cancer patients have significantly abnormal HRV compared to reference individuals,suggesting the presence of a certain level of cardiac autonomic dysfunction in this patient population.
基金Supported by National Agency of Research and Development(ANID),Government of Chile(https://anid.cl/about-us/),through the Initiation in Research FONDECYT grant No.11241548.
文摘Autonomic dysfunction(AD)is frequently observed in cirrhotic patients and is associated with poor clinical outcomes and prognoses.Heart rate variability(HRV),a noninvasive tool for assessing autonomic nervous system balance,has been extensively studied in a variety of conditions,including chronic liver disease(CLD);however,no recent reviews have focused on its role in CLD.This article examines the mechanisms of AD in CLD and the foundation for HRV assessment,highlighting its diagnostic,prognostic,and therapeutic applications in CLD,including liver transplantation(LT).Changes in HRV,particularly in patients with cirrhotic complications,and its prognostic significance throughout the natural history of CLD are summarized.We show that HRV is consistently reduced in CLD patients,reflecting AD,and is inversely correlated with liver disease severity.Also,low HRV is associated with complications such as hepatic encephalopathy,ascites,and portal hypertension.Moreover,evidence indicates that reduced HRV is an independent risk factor for mortality and circulatory instability in CLD.Furthermore,treatment with beta-blockers and LT improves HRV,underscoring its potential role in patient management.While further studies are needed,HRV emerges as a promising tool for the comprehensive evaluation and clinical management of patients with CLD,offering insights into disease progression and therapeutic response.
基金We acknowledge that the research is supported by the National Key Technology Research and Development Program(No.2012BAK17B15).
文摘This paper presented a novel variable rate fertilization system based on the method of adjusting the active feed-roll length of a fluted roller.The feasibility of this method was discussed using analysis of the fluted roller model.One seed drill produced by Kuhn Company(France),which could sow and fertilize simultaneously,was used as a test platform to implement the mechanical structure of variable rate fertilization.The design methods for the variable rate fertilization mechanical structure and actuator were introduced in detail.A low-cost and stable embedded support decision subsystem and corresponding software were developed.The support decision subsystem is based on grid management.Each grid field cell contains information about corresponding spatial position and fertilizer application rate.A SpatiaLite database was employed to solve the spatial location search and spatial data query.Experiments were conducted to evaluate the fertilization uniformity and dynamic response time.The average value of coefficient of variation is 8.4%in five different active feed-roll lengths which reflects good uniformity.The dynamic response times for the adjustment of variable rate fertilization system from 204 kg/hm^(2) to 319 kg/hm^(2) and 319 kg/hm^(2) to 204 kg/hm^(2) are about 4.2 s.The results suggest that the variable rate fertilization system performs well in dynamic adjustment and stability.
基金The authors acknowledge that this work was financially supported by Special Fund for Agro-scientific Research in Public Interest(No.201503130)Beijing Science and technology plan projects(No.D171100002317003)National Natural Science Foundation of China(31470099).
文摘During different growth periods,canopy size and density in orchards are variable,which need application conditions(flow rate and air flow)to be adjusted to match the canopy’s characteristics.In order to improve orchard sprayer’s automatic operating performance,an automatic variable-rate orchard sprayer(VARS)fixed with 40 electromagnetic valves and 8 brushless fans was developed based on the canopy’s spatial dimensions.Each solenoid valve and brushless motor can be individually adjusted in real-time through pulse width modulation(PWM)signals emitted by a control system to adjust each nozzle’s spout and fan rotation speed.A high-precision laser scanning sensor(light detecting and ranging,LIDAR)was adopted as the detector to measure the canopy volume using the variable rate algorithm principle.Field experiments were conducted in an apple orchard,and conventional air blast sprayer(CABS)and directed air-jet sprayer(DAJS)were tested as a comparison.Results showed that on average,46%less spraying solution was applied compared to conventional applications,while penetration rate was similar to DAJS.Normalized deposition in the canopy with variable application was higher than that of conventional applications,indicating that electronic sprayers are more efficient than conventional sprayers.It was also observed that VARS could significantly reduce off-target loss.The field experiment showed that the newly developed variable-rate sprayer can greatly reduce pesticide use and protect the environment for the orchard fruit production,and also provide a reference for design and performance optimization for plant protection machinery.
基金We acknowledge that the research was financially supported by Research and Demonstration of Key Technologies for Water Saving in Irrigation Areas in Guangdong Province based on UAV(2016-18)Research and Demonstration of Key Technology for Precision Spraying of Agricultural UAV based on Multi-source Information(201803020022).
文摘The rapid developments of unmanned aerial vehicles(UAV)and vision sensor are contributing a great reformation in precision agriculture.Farmers can fly their UAV spraying pesticides around their crop fields while staying at their remote control room or any place that is separated from their farm land.However,there is a common phenomenon in rice planting management stage that some empty areas are randomly located in farmland.Therefore,a critical problem is that the waste of pesticides that occurs when spraying pesticides over rice fields with empty areas by using the common UAV,because it is difficult to control the flow accuracy based on the empty areas changing.To tackle this problem,a novel vision-based spraying system was proposed that can identify empty areas automatically while spraying a precise amount of pesticides on the target regions.By this approach,the image was preprocessed with the Lucy-Richardson algorithm,then the target area was split from the background with k-means and the feature parameters were extracted,finally the feature parameters were filtered out with a positive contribution which would serve as the input parameters of the support vector machine(SVM)to identify the target area.Also a fuzzy control model was analyzed and exerted to compensate the nonlinearity and hysteresis of the variable rate spraying system.Experimental results proved that the approach was applicable to reducing the amount of pesticides during UAV spraying,which can provide a reference for precision agriculture aviation in the future.
基金This work was carried out with the support of the“Cooperative Research Program for Agriculture Science&Technology Development”(Project No.PJ01050303),Rural Development Administration,Republic of Korea.
文摘Environmental impact and economic concerns have driven a variable rate technology(VRT).Spinner spreaders were mainly used for granular fertilizer application since they are simple in design,inexpensive,and can cover large areas.However,the spreader was not adequate for VRT because uniformity changes drastically while varying application rates.Thus,the purpose of this study was to develop a variable rate applicator with uniform spreading patterns.A commercial spreader was modified with a controller and electric actuators for controlling fertilizer discharge directions and amounts.Database was established to determine the optimum discharge direction according to the fertilizer application amount.The uniformity of spreading patterns in accordance with the spread amount per set unit area was evaluated by the statistical coefficient of variation(CV)lower than 15%is assumed to prevent damage to the crop.Test results showed that CVs were 8%,9%,and 8%,respectively,for a tractor in race track mode(adjacent passes in same direction of travel)at 200 kg/hm^(2),300 kg/hm^(2),and 400 kg/hm^(2).This indicates that the fertilizer was spread uniformly,while the coefficient of variation was 12%at 200 kg/hm^(2) in back and forth mode(adjacent passes in the opposite direction of travel).Overall,the results suggest that the race track mode is suitable for operation of a tractor to ensure uniform spreading of fertilizer when applying at variable rates.The future goal is to establish a system for automatic variable rate application according to location in connection with soil analysis and geographic information systems.
基金The authors express appreciation for the financial support provided by National Key Technologies R&D Program of China(No.2017YFD0700305 and No.2016YFD0200600-2016YFD0200602-4)Fundamental Research Funds for Central Non-profit Scientific Institution(S201712).
文摘The key technical problem of variable rate fertilization system based on spectrum information was precise variable fertilization in certain area according to the acquired spectrum information.Hysteretic fertilizing is a critical problem in most of current fertilizer equipment.Hysteresis model was built and analyzed in this study to improve the system.Fertilizing tests were conducted on different wheat breeds and the results were analyzed.The tests showed that variable rate fertilization had obvious hysteresis phenomenon with the maximum lag distance of 3.82 m,the minimum lag distance of 1.73 m and average of 3.06 m.Hysteresis phenomenon of the variable rate fertilization system was obviously decreased when implanting a correction time of 2.04 s with the maximum lag distance of 0.61 m.Variable effects varied by different wheat breeds.Variable rate fertilization had an advantage of improving spatial differences of Yangmai-23,and the spatial variability of which decreased by 14.23%.In the small test area,the amount of fertilizer in Zhenmai-168 decreased by 2.84 kg,while the amount of which in Yangmai-23 increased by 3.83 kg.Yield of Zhenmai-168 in small area was lower than that in traditional pattern,but the condition of Yangmai-23 was on the contrary.Valuable information for increasing performance of fertilization in variable rate fertilization system was provided in this paper.
基金The authors acknowledge that this work was financially supported by the National Natural Science Foundation of China(No.31401284)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(No.2014BAD06B03).
文摘In order to improve soil fertility and fertilizer utilization,a subsoiling variable rate fertilization machine based on conservation tillage and precision agriculture was designed and tested.The relationship between suspension parameters and penetrating distance was analyzed,and a matching model between fertilizing quantity and penetrating distance was established.The variable rate fertilization control machine was developed based on an Advantech PCM-9363 industrial control mainboard.The machine operates under two patterns:DGPS-based positioning and straight-line path positioning based on a planar coordinate system.This machine can perform on-demand fertilization according to the spatial differences in soil nutrients and the prescription maps pre-set before the operation.Field experiments showed the machine has a subsoiling stability of 92.5%,a soil breaking rate of 61.1%,a maximum positioning relative error of 2.68%and a maximum variable rate fertilization error of 3.89%.The subsoiling performance and variable rate fertilization indices of this machine satisfy the requirements of GB/T24675.2-2009.The tested indices meet the national and industrial standards and satisfy the design requirements.The findings of the research can be used as the structural design of the subsoiling variable rate fertilization machine.
基金Project supported by the National Natural Science Foundation of China(No.61174024)
文摘To address the problem of maneuvering target tracking, where the target trajectory has prolonged smooth regions and abrupt maneuvering regions, a modified variable rate particle filter （MVRPF） is proposed. First, a Cartesian-coordinate based variable rate model is presented. Compared with conventional variable rate models, the proposed model does not need any prior knowledge of target mass or external forces. Consequently, it is more convenient in practical tracking applications. Second, a maneuvering detection strategy is adopted to adaptively adjust the parameters in MVRPF, which helps allocate more state points at high maneuver regions and fewer at smooth regions. Third, in the presence of small measurement errors, the unscented particle filter, which is embedded in MVRPF, can move more particles into regions of high likelihood and hence can improve the tracking performance. Simulation results illustrate the effectiveness of the proposed method.
